Throttle dashpot



75R REFERENCE SEARCH ROOM June 8, 1954 G. w. HARRY THROTTLE DASHPOT Filed May 10, 1951 Patented June 8, 1954 THROTTLE DASHPO'I Gordon W. Harry, Flushing, Miclr, assignor to General Motors Corporation, Detroit, Mich, a

corporation of Delaware Application May 10, 1951, Serial No. 225,497

15 Claims. 1

This invention relates to pneumatic devices for resisting or retarding the movement of other devices in one or more directions and more particularly to devices of this character adapted for use with automotive or other internal combustion engines to prevent stalling when the throttles thereof are suddenly released.

One object of the present invention is to provide a reliable and highly improved 'antistall means for internal combustion engines.

Another object is to provide an antistall device which is adapted for ready installation on internal combustion engines now in use as well as on those in the process of manufacture.

A further object is to provide a dash pot of the diaphragm type in operative association with the carburetors of automotive engines to prevent stalling of the latter when their control throttles are suddenly released.

A still further object is to provide a dash pot of the stated character which is simple in construction, economic in manufacture and highly efficient in operation.

A still further object is to provide a variable chamber mechanism wherein the chamber is divided into two compartments by a diaphragm and wherein the said diaphragm and the supporting plates therefor provide valve means to permit fluid flow through the said diaphragm during movement of the latter in one direction.

Other and further objects will become apparent .as the description of the invention progresses.

Of the drawings:

Fig. l is a fragmentary elevational view of an automobile engine carburetor having the antistall device incorporating the present invention operatively connected with throttle control means associated therewith.

Fig. 2 is a longitudinal sectional view of the antistall device taken substantially along line 2-2 of Fig. l, and

Fig. 3 is an exploded perspective view of several of the operating parts of the antistall device shown in Figs. 1 and 2.

Referring to the drawing and more particularly to 1 thereof, the numeral .10 indicates a portion of a downdraft carburetor which .is adapted for operative connection tov an automotive or other internal combustion engine (not shown).

A throttle valve (not shown) having an operating shaft H is provided in carburetor l0. Shaft ll projects through a coupling l2 which connects the carburetor III to the manifold of the engine with which the said carburetor is employed. A valve operating lever 13 actuable by a rod 14 is secured to the flattened end of shaft II as shown in Fig. 1. One end of rod M is pivotally connected to lever I3 as shown at If; .while the opposite end of said rod may be connected to an accelerator pedal or other suitable device for actuating lever Hi from any remote position, by means of links and levers or other intermediate connecting means (not shown).

The throttle for carburetor ID has a suitable idling position at which it is partly open at all times for the purpose of admitting to the engine a sufficient charge of fuel to maintain the said engine in operation at low speed and generally at no load. Such idling position of the throttle for the carburetor 10 is determined by a screw I! which is adjustably secured in a threaded opening formed in a part 18 of the lever I3. The opposite end of the screw i1 beyond the part I8 is adapted to engage any suitable stop projecting from the casing of the carburetor iii. A suitable spring not shown but generally associated with rod I4 is adapted to resiliently urge lever l3 into a position in which the end of the screw I! will engage the stop referred to.

It will be apparent from the structure disclosed that the throttle valve will be opened when the lever I3 is rotated in a counterclockwise direction by pulling upon rod l4 and will be moved toward closed-or to idling position when the lever I3 is rotateddn an opposite direction by an opposite movement of the rod 14 and into a position in which the screw l'l engages the idling stop referred to.

The lever I3 is also provided with a laterally projecting arm H! which is adapted to engage and operate in one direction the actuating rod or shaft 2| of an antistall device indicated generally by numeral 22. .Antistall device 22 is provided with a casing 23 comprising two sections .24 and 26, which, as will appear more fully later herein, are secured together at their outer rims. Rod 21. it will be observed, extends through the bore .21 of an externally threaded sleeve, .28. The reduced inner-end 2.9 of sleeve 28 extends through an opening 3 provided in a cup-shaped depression 33 dis;v sad centrally of casing section 26, the outer wall 32 or said depression in assembly, abutting the annular shoulder 33 on said sleeve 28. When the parts have been so assembled the wall 32 of depression 3| is welded or otherwise rigidly secured to the reduced end 29 of sleeve 28. Antistall device 22 is secured to a bracket 3 which in turn is secured in any suitable manner to the casing of carburetor it. As shown in Figs. 1 and 2, bracket 34- has a relatively flat supporting portion 35 provided with an opening 36 for receiving sleeve 28. A spacing washer 3'! is disposed between and engages supporting portion 35 and the inner end of a nut 38 making threaded engagement with sleeve 28. The outer wall 32 of depression 3! is rigidly secured to fiat portion 35 of bracket 34 by welding or by any other suitable means. Thus when nut 38 is tightened washer 3? is brought into intimate contact with the supporting portion 35 of bracket 34. The antistall unit is therefore effectively held in proper position on bracket 34.

A stud 39 having a head 40 is press fitted into the outer tubular end of rod 2 i. The stud 39, obviously, may be forced into the openin in shaft 2| to any desired extent. The length of rod 2| thus may be adjusted to the proper position with respect to throttle lever i3 of the carburetor H3. The antistall device 22 is in proper position on bracket 34 when the axis of the rod 2| makes substantially a right angle with a line passing through the axis of shaft 1| and the point of engagement of arm l9 and stud 39 when the throttle operating lever I3 is in engine idling position Casing section 24 comprises an outwardly depressed cup-shaped portion 4 offset annular end walls 42' and 42 and an inwardly and upwardly inclined annular wall 43 which terminates in a vertically disposed rim or flange 44. The casingsection 26, in addition to the cup-shaped clepressed portic-n 3| also comprises a substantially vertical annular end wall 45 and an upwardly and inwardly inclined annular wall 46 which terminates in a vertical outer rim or flange 4?. A flexible diaphragm 48 is secured between the flanges ii? and 47 of easing sections 24 and 26 by crimping the outwardly projecting flange 41 around flange H as shown at 49 in Fig. 2.

The central portion of diaphragm 48 is reinforced on either side thereof by a pair of sub stantialiy circular valve plates 59 and Plates 5G and 5| have oppositely disposed flanges 52 and 53, respectively, provided on the peripheral edges thereof, flange 52 being adapted to engage end wall 42 of casing section 24 to limit the movement of diaphragm 48 in one direction while flange 53 is adapted to engage end wall 45 of easing section 26 to limit the movement of said diaphragm in the opposite direction.

A coil spring 55 having one end disposed within and engaging the outer wall of depressed portion 4| of casing section 24 and the opposite end abutting the central portion of plate 50, tends to resiliently urge the diaphragm 48 to the right or what might be termed as the expanded position of the diaphragm. In such position of diaphragm 48 the flange 53 of plate 5| rests against the end wall 135 of casing section 26, as shown by broken lines in Fig. 2. moved toward and away from-the expanded position referred to by the shaft 2| which isoperatively connected to the said diaphragmand The' diaphragm 45 is the plates and 5| by securing means which will be later described.

Diaphragm 48 divides casing 23 into two compartments or chambers 56 and 5'! and certain valve means are provided which enable air to flow freely between said compartments when the said diaphragm moves to the right or to the expanded position and which causes restricted flow between said compartments when the diaphragm moves to the left or toward idling position. Diaphragm 48 and plates 50 and 5| each have provided centrally thereof a key shaped opening 58 having a substantially semicircular lower portion 59 for receiving the correspondingly shaped inner end 60 of rod 2| and an upper relatively short and narrower portion 8! communicating therewith. Disposed between the inner end 60 and shaft 2| proper the latter also has provided thereon an enlarged portion 62 having an annular axially extending flange 63 disposed near the periphery of the inner side thereof forming a recess 54. A metering plate 65 is disposed between flange 53 and plate 5| and also has a substantially semicircular open ing E6 therein for receiving the inner end 68 of shaft 2| and a relatively long and narrow metering slot 67. the slots 6|, and, as shown in Fig. 2 extends above the periphery of the enlarged portion $2 of rod 2| so as to communicate with compartment 51. A breather plate 68 having a substantially semicircular opening es therein for receiving the inner end 66 of rod 2| engages plate as. The innermost end of rod 2| has a substantially cylindrical portion 10 provided thereon for receiving a holding washer l After the parts have been assembled on the inner end of rod 2| the cylindrical portion is peened over washer ll thereby securely clamping the parts in position. Breather plate 88 has provided therein depressions 12 and 13 disposed at substantially right angles to each other and extending across opening 59 thereby forming passages between plates 68 and 55 which communicate with slots 6| and through which small amounts of air may flow to and from compartment 53. Diaphragm 48 and plate 50 have aligned openings 14 and i5, respec tively, therein through which air may rapidly flow from compartment 51 to compartment 58 when diaphragm 48 moves to the right or expanded position. When diaphragm 48 moves to the left or toward engine idling position opening 15 is closed by plate 5 and consequently air from compartment ES may flow to compartment 5! only through the depressions in breather plate 68 and slots 5| and E1. The recess 84 providedbetween enlafge'd portion E2 of shaft 2| and plate 5| communicates with the passages formed by slots 6| and 62. The passages defined by the slots 6| and 61 are so designed that the cross sectional area of slot 6? through which air from compartment 55 escapes into compartment 51 or through which air from compartment 5? flows to compartment 56 constitutes the most restricted portion of the passage and consequently any desired amount of air to be metered may be obtained by merely changing the size ofslot B1. 7

Plate 56, it will be observed, is dished so that the annular portion thereof extending from and beyond opening l5 diverges from plate 5| forming a space H5 therebetween. By this construction of plate 58 diaphragm GS'is adapted to move relative-toplat'es 5|) and 5| from the position hown in Fig. 2 against plate 5| wherein open- Slot 6! is in axial alignment with ing '14 is closed to a position against plate 50 wherein opening '74 is spaced from plate 51 and consequently air may fiow freely between compartments 56 and 5'! through openings 14 and 15.

From the foregoing description it seen that when the throttle is opened or moved away from the idling position by pulling on red M and thereby rotating lever l3 in a counterclockwise direction, spring 54 will cause rod 21 to follow arm [9 until the diaphragm reaches its expanded pom"- tlon.

Upon the initial movement of diaphragm 58 away from casing section '24 a reduction is pres.- sure occurs in chamber 56 and an increase of pressure in chamber 51 caumng diaphragm 48 to move away from plate 5! toward plate 58 thereby uncovering opening M and permitting air to flow freely from compartment 51 to compo-rt ment 55. Spring 54, therefore, encounters little resistance and as a result the movement of diaphragm 48 and shaft 2| is as rapid as that of lever l3 which the said shaft follows. When in fully expanded position the flange 53 on plate 51 is in engagement with the end wall 45 of casing section 2 The parts remain in this position until rod [4 actuates lever IS in a clockwise direction at which time arm [9 acting on Stud 39 at the end 'of lever moves the latter to the left against the pressure of spring 54. Upon initial movement of rod 2| in this manner the pressure in chamber 5'! is slightly reduced while the pressure inschamber 56 increases, and, consequently, the diaphragm 48 is moved against plate 5| thereby closing the opening 14 in said diaphragm. All air flowing from compartment 56 to compartment 5'! must now fiow through the passages between breather plate 58 and plate 50 and slots El and 61. As a result the movement of diaphragm 48 to the left or to idling position is relatively slow and therefore movement of the throttle to idling position is gradual. Stalling of the engine by a sudden or rapid movement of the throttle to idling position from a more open position thereof is thus effectively prevented. When diaphragm 48 reaches idling position the flange 52 on plate 50 abuts end wall 4-2 of casing section 24.

From the foregoing description it is seen that a simplified and highly improved antistall device has been provided. comprised of but a few simple parts efficient operation thereof is assured over a long period of time.

It will be apparent that changes and modifications may be made in the device disclosed without departing from the invention. It is also apparent that the invention shown and described herein is adapted for wide and varied uses other than that as a dash not. It is intended, therefore, that the invention should be limited only by the scope of the claims which follow.

What is claimed is:

1. A dash pot, comprising. a casing, a diaphragm dividing said casing into two compartments, a circular plate disposed at either side of said diaphragm, one of said plates being dished to provide a space between said plates over a portion of the area thereof, one of said plates and said diaphragm having aligned openings therein positioned opposite said portion, through which air may freely flow between said compartments when said diaphragm is moved in one direction and through which airflow is prevented when said diaphragm is moved in the other direction, means providing a restricted passage between Inasmuch as the device is i said compartments, and operating means for said diaphragm.

-2. A dash pot comprising a casing, a diaphragm dividing said casing into two compartments, :1. plate disposed adjacent one side of said diaphragm, said plate and diaphragm having aligned openings therein, a second plate disposed adjacent the other side of said diaphragm and adapted to cover the said opening in said diaphragm when the latter moves in one direction, said diaphragm moving away from said second plate when actuated in the opposite direction, a dished portion on one of said plates providing a space between said plates permitting air to flow between said compartments through said openings when said diaphragm moves in said opposite direction, means providing a restricted passage between said compartments, and operating means for said diaphragm.

3. A dash pot, comprising, a casing, a diaphragm dividing said casing into two compartments, a plate disposed adjacent one side of said diaphragm, said plate and diaphragm having aligned openings therein through which air may flow between said compartments, second plate disposed adjacent the other side of said diaphragm adapted to cover the said opening in said diaphragm when the latter is moved in one direction, said diaphragm moving away from said plate to uncover said opening when moved in the opposite direction, an annular dished portion on said first plate extending from the opening therein to the outer end thereof providing a space between said plates to permit air to flow between said compartments through said openings when said diaphragm moves in said opposite direction, and operating means for said diaphragm and plates.

4. A throttle dash pot for internal combustion engines, comprising. a casing, diaphragm dividing said casing into two compartments, valve plate disposed on each face of said diaphragm, one of said plates and diaphragm having aligned openings therein through which air may freely flow between said compartments when said diaphragm moves in one direction, the other of said plates engaging the face of said diaphragm and being adapted to close the said opening in said diaphragm when the latter moves in the opposits direction, said. diaphragm and valve plates having aligned slots therein, a breather plate disposed adjacent one of said valve plates forming therewith one or passages communicating with said aligned slots. 2. metering plate disposed adjacent the other of said valve plates having a metering opening therein communicating with said aligned slots. an operating rod for said diaphragm, means on said rod for supporting said plates, and means for clamping together said plates and diaphragm on said rod.

5. A throttle dash pot. comprising. a casing, a diaphragm having an air opening therein and dividing said casing into two compartments, a valve plate disposed at either side of said diaphragm for controlling the flow of air between said compartments through the said opening in said diaphragm, a breather plate disposed adjacent one of said plates and forming therewith one or more air passages, an air metering plate disposed adjacent said other valve plate having a metering slot therein, said diaphragm and valve plates having aligned slots therein forming an air passage oomrmmicating with the passages in said breather plate and said metering slot, an operating rod for said diaphragm and plates mounted for reciprocation in said casing, supporting means on said rod of substantially semicircular cross sectional shape for said valve, breather and metering plates and said diaphragm, said valve, breather and metering plates and said diaphragm having openings therein corresponding to said supporting means for receiving the latter, and means for securing said valve, breather and metering plates and said diaphragm in position on said supporting means.

6. A throttle dash pot, comprising, a casing, a diaphragm mounted in said casing dividing the latter into two compartments, and valve means for controlling the rate of movement of said dia phragm, said last mentioned means comprising a valve plate disposed at either side of said diaphragm, one of said valve plates and said dia phragm having aligned openings therein through which air freely pass between said compartnients when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in the opposite direction, means provided on one of said plates to permit a limited relative movement between said diaphragm and said valve plates to effect opening and closing of the opening in said diaphragm, an operating rod mounted in said casing, means on said rod for supporting said plates, means for clamping said plates to said diaphragm, and means providing a relatively small passage between said compartments hrough which small quantities of air may pass, thereby retarding the movement of said diaphragm in the said opposite direction.

'7. A throttle dash pot, comprising, a sectional casing, a diaphragm secured between the sections of said casing dividing the latter into two compartments, an operating rod for said diaphragm extending through and mounted for reciprocation centrally of one of said casing sections, and valve means for controlling the rate of movement of said diaphragm, said means comprising a valve plate disposed at either side of said diaphrag. one of said valve plates and said diaphragm having aligned openings therein through which air may freely flow between said coinpartments when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in the opposite direction, one

of said valve plates being dished so as to provide a space between said valve plates to permit relative movement of the latter and said diaphragm to sheet opening and closing of the said opening in said diaphragm, means on said rod for supporting said plates, means for clamping said plates to said diaphragm, and said valve plates and diaphragm having aligned slots therein adjacent said rod through which relatively small amounts of air may flow between said compartments, thereby retarding the movement of said phragm in said opposite direction.

8. A throttle dash pot, comprising, a sectional casing, a diaphragm secured between the sections of said casing dividing the latter into two compartments, an operating rod for said diaphragm extending through and mounted for reciprocation centrally of one of said casing sections, and valve means for controlling the rate of movement of said diaphragm, said means comprising a valve plate disposed at either side of said diaphragm, one of said valve plates and said diaphragm having aligned openings therein through which air may freely flow between said compartments when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in the opposite direction, one of said valve plates being dished so as to provide a space between said valve plates to permit relative movement of the latter and said diaphragm to efiect opening and closing of the said opening in said diaphragm, said valve plates and diaphragm having aligned slots therein, air metering means disposed adjacent one of said valve plates for controlling the flow through said slots of small amounts of air between said compartments thereby retarding the movement of said diaphragm in said opposite direction, supporting means on said rod for said plates and metering means, and means for clamping together said valve plates, diaphragm and metering means on said rod so as to move as a unit therewith.

9. A throttle dash pot, comprising, a sectional casing, a diaphragm secured between the sections of said casing dividing the latter into two compartments, an operating rod for said diaphragm extending through and mounted for reciprocation centrally of one of said casing sections, and valve means for controlling the rate of movement of said diaphragm, said means comprising a valve plate disposed at either side of said diaphragm, one of said valve plates and said diaphragm having aligned openings therein through which air may freely flow between said compartments when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in the opposite directions, one of said valve plates being dished so as to provide a space between said valve plates to permit relative movement of the latter and said diaphragm to effect opening and closing oi. the said opening in said diaphragm, said valve plates and diaphragm having aligned air slots therein adjacent said rod, a breather plate disposed adjacent one of said valve plates, and forming therewith one or more passages for air communicating with said air slots, a metering plate disposed adjacent the other of said valve plates having an air metering slot therein communicating with said first mentioned slots through which relatively small amounts of air may flow between said compartments, thereby retarding the movement of said diaphragm in the said opposite direction, supporting means on said rod for said valve, breather and metering plates, and means for clamping together said breather valve and metering plates and said diaphragm on said rod so as to move together as a unit with the latter.

10. A throttle dash pot, comprising, a sectional casing, a diaphragm secured between the sections of said casing dividing the latter into two compartments, an operating rod for said diaphragm extending through and mounted for reciprocation centrally of one of said casing sections, and valve means for controlling the rate of movement of said diaphragm, said means comprising a valve plate disposed at either side of said diaphragm, one of said valve plates and said diaphragm having aligned openings therein through which air may freely flow between said compartments when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in the opposite direction, one of said valve plates being dished so as to provide a space between said valve plates to permit relative movement of the latter and said diaphragm to effect opening and closing of the said opening in said diaphragm, said valve plates and diaphragm having aligned slots there in, air metering means disposed adjacent one of said valve plates for controlling the flow through said slots of small amounts of air between said compartments thereby retarding the movement of said diaphragm in said opposite direction, supporting means on said rod for said plates and metering means, means for clamping together said valve plates, diaphragm and metering means on said rod so as to move as a unit therewith, a spring disposed between one of said casing sections and one of said valve plates for actuating said diaphragm in said one direction, and a throttle valve actuating lever engaging said rod to operate said diaphragm in the said opposite direction.

11. A throttle dash pot, comprising, a sectional casing, a diaphragm secured between the sections of said casing dividing the latter into two compartments, an operating rod for said diaphragm extending through and mounted for reciprocation centrally of one of said casing sections, and valve means for controlling the rate of movement of said diaphragm, said means comprising a valve plate disposed at either side of said diaphragm, one of said valve plates and said diaphragm having aligned openings therein through which air may freely flow between said compartments when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in the opposite direction, one of said valve plates being dished so as to provide a space between said valve plates to permit relative movement of the latter and said diaphragm to effect opening and closing of the said opening in said diaphragm, said valve plates and diaphragm having aligned slots therein, air metering means disposed adjacent one of said valve plates for controlling the flow of small amounts of air through said slots thereby retarding the movement of said diaphragm in said opposite direction, supporting means on said rod for said plates and metering means, means for clamping together said valve plates, diaphragm and metering means on said rod so as to move as a unit therewith, a spring disposed between one of said casing sectionsand one of said valve plates for actuating said diaphragm in said one direction, a throttle valve actuating lever engaging said rod to operate said diaphragm in the said opposite direction, and stop means on said valve plates engaging said casing sections to limit the movement of said diaphragm in either direction.

12. A throttle dash pot, comprising, a sectional casing, a diaphragm secured between the sections of said casing dividing the latter into two compartments, an operating .rod for said diaphragm extending through and mounted for reciprocation centrally of one of said casing sections, and valve 'means for controlling the rate of movement of said diaphragm, said means comprising a valve plate disposed at either side of said diaphragm, one of said valve plates and said diaphragm having aligned openings therein through which air may freely flow between said compartments when said diaphragm moves in one direction, the other of said plates being adapted to close the said opening in said diaphragm when the latter moves in theopposite direction, one of said valve plates being dished 10? so as to provide a space between said valve plates topermit relative movement oi the latter and said diaphragm to effect opening and closing of the said opening in said diaphragm, said valve plates and diaphragm having aligned air slots therein adjacent said rod, a breather plate disposed adjacent one of said valve plates, and forming therewith one. or more passages for air communicating with said air slots, a metering plate disposed adjacent the other of said valve plates having an air metering slot therein communicatwith said first mentioned slots through which relatively small amounts of air may flow between said compartments, thereby retarding the movement of said diaphragm in the said opposite direction, supporting means, on said rod for said valve, breather and metering plates, means for clamping together said breather valve and metering plates and said diaphragm on said rod so as to move together as a unit with the latter, a spring disposed between one of said casing sections and one of said valve plates for actuating said diaphragm in said one direction, a lever engaging said rod to operate said diaphragm in the said opposite direction, and stop means on said valve plates engaging said casing sections to limit the movement of said diaphragm in either direction.

13. In a diaphragm controlled pressure difierential chamber, a casing having an interior cavity, a diaphragm unit dividing said cavity into two compartments, said diaphragm unit including a flexible diaphragm and a pair of plates disposed on opposite sides of said flexible diaphragm, said diaphragm unit having a valve portion, one of said plates being dished to provide a space between said plates for free movement of said flexible diaphragm at said valve portion of said diaphragm unit, one of said plates and said flexible diaphragm having aligned openings therein positioned in said valve portions of said diaphragm unit through which air may freely flow between said compartments when said diaphragm unit is moved in one direction and said flexible diaphragm contacts said one of said plates having an opening, and flow through said openings is prevented when the diaphragm unit is moved in the other direction and said flexible diaphragm contacts the other plate with respect '2 to said one of said plates having an opening, and

operating means for said diaphragm unit.

14. A variable chamber mechanism having a chamber divided into two portions by a diaphragm, said diaphragm having a one-way valve mechanism, said valve mechanism comprising an opening in said diaphragm, a pair of plates disposed on opposite sides of said diaphragm, one of said plates having an opening aligned with said diaphragm opening, the other of said plates adapted to close said diaphragm opening when the diaphragm is moved in one direction, said diaphragm being adapted to move away from said other plate when moved in the opposite direction, one of said plates having a dished por- 7 tion providing a space between it and the other plate permitting flow of fluid between said chamber portions through said diaphragm and plate openings when the diaphragm is moved in said opposite direction, and operating means for said diaphragm.

15. A diaphragm controlled pressure difierential chamber comprising, a casing, a diaphragm attached to said casing and separating said casing into two chambers, an aperture formed in said diaphragm, a rigid plate mounted adjacent 11 to said diaphragm having a portion adapted to close said aperture, said plate being mounted so that the plane of the closing portion of said plate is substantially parallel to the plane of the diaphragm in the area of said aperture and. 5

References Cited in the file of this patent UNITED STATES PATENTS Number Number 345,624

Name Date Templin Feb. 2 1935 Kuhn Feb. 20, 1940 Gould Dec. 29, 1942 FOREIGN PATENTS Country Date Great Britain Mar. 24, 1931 

